3 Major Muscle Milk Side Effects

Muscle Milk has become a ubiquitous nutritional supplement drink. It’s found not only in supplement stores, but also at most corner markets.

Its ingredients, according to its website, include calcium and sodium caseinate, milk protein isolate, maltodextrin, fructose, potassium citrate, and vitamin mineral blend, among others. But because you can’t pick “vitamin mineral blend” or some of the other ingredients from a tree, many people are wary of Muscle Milk and wonder if it’s safe for them.

Natalie Stephens, a registered dietitian and nutritionist at the Ohio State University Wexner Medical Center, acknowledges the food label on Muscle Milk products can be a bit of a tongue twister for the average person.

But are there any known ingredients in Muscle Milk that people should be concerned about?

“While there aren’t any ingredients that are outright harmful, this question really depends on the individual consumer,” she says. “People with chronic diseases like high blood pressure, kidney issues, or sensitivity to food dyes or sugar substitutes may want to read closely or even ask the advice of a qualified health professional before consuming.”

Other experts disagree with Stephens due to Muscle Milk containing acesulfame potassium and sucralose. These two artificial sweeteners are known to interact with gut bacteria and may promote weight gain and insulin resistance.

Felice Kosakavich, MS, RD, CDN, has a son who plays college basketball and uses Muscle Milk as his protein supplement of choice.

“With excessive weight training and practices he feels it is a good price, excellent taste, and meets his needs for additional protein,” she says. “He is comfortable using it and, after much research, feels it is reputable.”

Kosakavich says athletes like her son could benefit from Muscle Milk. “The composition of high-protein, low-carbohydrates will provide the extra protein needed pre and post workout for recovery,” she says.

But that doesn’t mean the supplement drink comes without concerns for specific people.

In 2013, CytoSport, Inc. — the maker of Muscle Milk — agreed to pay $5.3 million in a class action lawsuit about its marketing language using the word “healthy.”

Prior to the suit, Muscle Milk claimed to contain “healthy fats,” but the lawsuit alleged the drinks contained as much total and saturated fat as Krispy Kreme doughnuts.

The artificial sweeteners contained in Muscle Milk are also of concern to some. The Center for Science in the Public Interest advises consumers to avoid these types of sweeteners, which can negatively alter gut bacteria, appear in breastmilk, and potentially increase the risk of certain diseases.

In 2011, the U.S. Food and Drug Administration sent a warning letter to CytoSport about their claim that Muscle Milk “contains no milk.” While Muscle Milk doesn’t contain actual milk, it does contain whey and casein proteins, which are derivatives of milk that may trigger an allergic reaction in some people.

Kosakavich explains that many people are unaware that the digestive symptoms they are experiencing are related to a food allergy.

People with kidney disorders should talk with their doctor before they take Muscle Milk or any other type of protein supplement. A 10-oz. bottle of Muscle Milk contains 18 grams of protein.

Some people with kidney disease need high-protein diets, while others need low-protein, Stephens says. “In both cases, it’s best to monitor potassium, sodium, and phosphorus intake — and there are a lot of sources of those nutrients in a single serving [of Muscle Milk],” she notes.

Because excess protein is metabolized and flushed through the kidneys, Muscle Milk can overwork the kidneys of people with kidney insufficiency, Kosakavich says.

“It is also very important to consume adequate and additional water to help flush the kidneys with additional protein intake,” she adds.

If you have any food allergies, are concerned about artificial sweetener consumption, have a chronic kidney condition, or require prescription medication, use caution when drinking Muscle Milk. Kosakavich recommends speaking to your doctor or dietitian before trying it. “While it’s touted to be a source of nutrition for those missing nutrients in their diet, I’d continue to recommend seeking out advice from a registered dietitian to find ways to meet your needs with a whole-foods diet,” she says.